Hi,
im using this module.
and i looked at its datasheet here
http://cristiansteib.github.io/Sim800l/info/SIM800+Series_AT+Command+Manual_V1.09.pdf
and ont page 190 it says it can detect interference on the signal, possible a jammer. i configured the APN and activate the GPRS, got an IP too and test the SMS send. i have a jammer so i test it with it but the SIM doesnt show up anything diferent from +SJDR: NO JAMMING
i configures diferent thresholds but no change like this command
AT+SJDR=1,3,100,0
it respond ok, the last 0 shows on the serial the status of the interference every 3000ms but it always says +SJDR: NO JAMMING. i know the jammer works cuz it also afects the wifi and my cellphone.
i hope anyone test this function before and can help me